<template>
	<div>
		<router-link tag="div" to="/" class="header-abs" v-show="showAbs">
			<div class="iconfont header-abs-back">&#xe624;</div>
		</router-link>
		<div class="header-fixed" v-show="!showAbs" :style="opacityStyle">
			<router-link to="/">
				<div class="iconfont header-fixed-back">&#xe624;</div>
			</router-link>
			景点详情
		</div>
	</div>
</template>

<script>
export default {
	name:'DetailHeader',
	data() {
		return {
			showAbs: true,
			opacityStyle:{
				opacity:0
			}
		}
	},
	methods:{
		handleScroll () {
			const top = document.documentElement.scrollTop;
			if(top > 60) {
				let opacity = top / 140
				opacity = opacity > 1 ? 1 : opacity
				this.opacityStyle = {
					opacity:opacity
				}
				this.showAbs = false
			} else {
				this.showAbs = true
			}
		}
	},
	activated() {
		window.addEventListener('scroll',this.handleScroll)
	},
	//在页面即将被替换成新的页面之前，解绑全局事件
	deactivated() {
		window.removeEventListener('scroll',this.handleScroll)
	}
}
</script>

<style lang="stylus" scoped>
@import '~styles/varibles.styl'	
.header-abs
	position:absolute
	left:.2rem
	top:.2rem
	width:.8rem
	height:.8rem
	line-height:.8rem
	border-radius:.4rem
	text-align:center
	background:rgba(0,0,0,.8)
	.header-abs-back
		color:#fff
		font-size:.4rem
.header-fixed
	z-index:3
	position:fixed
	top:0
	left:0
	right:0
	height:$headerHeight
	line-height:$headerHeight
	text-align:center
	color:#fff
	background:$bgColor
	font-size:.32rem
	.header-fixed-back
		position:absolute
		top:0
		left:0
		width:.64rem
		text-align:center
		font-size:.4rem
		color:#fff
</style>
